CANBERRA  The drought gripping Australia could be the worst in 1,000 years, government officials said on Tuesday, as Australia started to draw up emergency plans to secure long-term water supplies to towns and cities.

The drought affecting more than half of Australia's farmlands, already lasting more than five years, had previously been regarded as the worst in a century.

But officials from the Murray-Darling river basin commission told a water summit of national and state political leaders on Tuesday that analyses of the current prolonged drought now pointed to the driest period in 1,000 years.

"What we're seeing with this drought is a frightening glimpse of the future with global warming," the leader of the South Australian state government Mike Rann told reporters.

A spokeswoman for the Murray-Darling Basin Commission said the current consecutive years of drought had not been observed in the 114 years since records were first kept.

She said mathematical and probability analyses of the current dry spell found Australia was moving into what was possibly a one-in-1,000-year drought.

"We don't have the records to substantiate a one-in-100-year drought any more -- it's beyond that," she told Reuters.

Lack of winter rain has meant record-low inflows into the Murray-Darling river system, which drains an area the size of France and Spain combined and provides water to Australia's major agricultural areas.

The average inflow of water into the Murray River, which flows through three states, is 11,000 gigalitres a year. In the past five months it has received less than 600 gigalitres. One gigalitre is one billion litres.

Green groups have warned that towns and cities along the river system could run out of water if the drought goes into another year.

Prime Minister John Howard used the water summit to announce moves to investigate how to secure log-term water supplies for towns and cities along the Murray River.

The summit also approved a new weir across the Murray to provide emergency water, if needed, for the South Australian capital of Adelaide, a city of about one million people, which draws 40 percent of its drinking water from the Murray River.

But Howard, who remains sceptical about the impact of global warming, declined to publicly declare the drought the worst in 1,000 years. "All I know it is a very bad drought. It is the worst in living memory," Howard told reporters.

The Australian Democrats party criticised the summit, saying the meeting had ignored both the need to buy water back from farmers and irrigators, and the need to put a higher price on water use.

"Making water more expensive is not going to be popular, but it needs to be done," Democrats Senator Andrew Bartlett told reporters.